The present invention relates to an improved component for a prosthesis assembly used in replacing a natural joint. More particularly, the present invention relates to a prosthetic component designed to include an interrupted articular face for minimizing surface area of articulation between itself and either a natural or prosthetic member.
It is known to provide a prosthetic joint assemblies for acetabulums, knees, ankles, shoulders, elbows, and wrists. Components of prosthetic joints such as that shown in U.S. Pat. No. 4,068,342 to Townley et al., provide a face having a continuous surface area of articulation for its corresponding member. While conventional prosthetic components beneficially provide a low-friction articular face for the surface of accompanying member, interaction between the articulating component and the member can produce joint debris. Such debris is expelled into the patient and may cause adverse reactions in the surrounding bodily tissue.
Attempts have been made to prevent joint debris produced by prosthesis joint assemblies from entering surrounding bodily tissue. See for example, U.S. Pat. No. 4,731,088 to Collier, where a flexible enclosure is applied to a prosthetic joint to isolate the joint debris from the surrounding tissue. What is needed is an improved bearing component for a prosthesis assembly which includes a face that is formed to minimize surface area of articulation for the engaging accompanying member and thus minimize the production of joint debris.
One object of the present invention is to provide an improved prosthetic component for use in a prosthesis which includes a surface that minimizes the production of joint debris produced from articulating movement of a corresponding member on said surface.
Another object of the present invention is to provide a bearing component for use in a prosthesis which includes an interior that forms an internal cavity suitable for receiving a ball therein, the cavity having an interrupted articular face for engaging the ball.
Still another object of the present invention is to provide a bearing component for use in a prosthesis which includes an interior that maximizes available ball distribution within said bearing component and minimizes the production of joint debris upon articulating movement of the ball.
Yet another object of the present invention is to provide an improved prosthetic component for use in a prothesis assembly which includes an interior that forms an internal cavity suitable for receiving a ball therein. The cavity being formed to enhance joint stability and reduce wear between the interior and the ball.
Another object of the present invention is to provide an improved prosthetic component for use in a prosthesis assembly which includes an interrupted articular face for engaging a corresponding articulating member.
According to one embodiment of the present invention a bearing component for a prosthesis of the ball-joint type, is provided. The bearing component provides a spherically concave bearing surface for receiving a ball, the surface being defined by a plurality of bearing platforms integral with said component. Thus, the bearing surface minimizes available surface area of articulation for the ball and the production of joint debris.
According to another aspect of the present invention a bearing component is provided for use with a ball. The bearing component has a generally hemispherical interior providing an internal cavity with an interrupted articular face. The interrupted articular face engages the ball and is interrupted by at least one recess extending into its bearing surface. In this specification and in the claims, the words "generally hemispherical" are intended to cover the spherical ranges conventionally used in acetabular and glenoid cup bearings including less than hemispherical and, in some cases, slightly more than hemispherical.
According to yet another aspect of the present invention a bearing component is provided for use with a ball. The bearing component comprises an interior having an internal cavity for receiving the ball therein. The cavity is defined by a one-piece articular face having a generally hemispherical bearing surface defined by at least one bearing platform extending into the internal cavity for engagement with the ball.
According to another embodiment of the present invention a ball component is provided for use with either a natural or prosthetic socket. The ball component comprises an interrupted articular socket-engaging face which effectively reduces surface area of articulation between the ball and the socket. The interrupted articular socket-engaging face rests against the socket and is interrupted by at least one recess extending into its surface. In this specification and in the claims, the words "ball component" are intended to cover prosthetic components for either the femoral or humeral head. Such ball components may be attached to an appropriate femoral or humoral stem.
According to another embodiment of the present invention a prosthetic patellar implant is provided for use with a natural or prosthetic knee. The patellar implant includes a patellum facing surface and a contoured interrupted surface opposite the patellum facing surface. The contoured interrupted surface engages either a natural or prosthetic distal end of a femur and is interrupted by a plurality of bearing platforms integral with said surface.
According to yet another embodiment of the present invention a prosthetic component is formed for replacing the extreme distal portion of the femur or the humorous and for attachment to either a prosthetic or natural femoral/humoral stem. The prosthetic component includes two interrupted condyles or articular surfaces that are configured to replace the smooth, uninterrupted condyles of the extreme distal portion. The condyles provide a convex interrupted bearing surface for engagement with medial and lateral condyles of a tibia or the condyle(s) of the radius and/or ulna. The interrupted articular surface of the prosthetic component is defined by a plurality of bearing platforms integral with the component.
According to yet another embodiment of the present invention, a prosthetic component is formed for replacing an extreme proximal portion of the tibia, radius, or ulna and in particular the medial and lateral condyles of the tibia or the condyle(s) of the radius and/or ulna. The prosthetic component is formed to include at least one slightly concave interrupted bearing surface. The interrupted bearing surfaces are formed to receive either a natural or prosthetic extreme distal portion of the femur or humorous, the surfaces being defined by a plurality of bearing platforms integral with the component. Thus, the bearing surface minimizes available surface area of articulation for the component and the production of joint debris.
The bearing components of the present invention are formed to reduce surface area of articulation between corresponding articulating bearing components. Because the articular face is interrupted by recesses and/or protrusions, the interrupted articulation surface will be maintained despite minimal wear that may occur at the point of contact between the bearing components. This reduction in surface area is intended to lead to a decrease in the production of joint debris which contributes to both wear debris incited osteolysis and eventually to failure of the prostheses assembly.
Other objects and features of the present invention will become apparent as this description progresses.